Abstract

Cross sections, angular distributions and forward-backward asymmetries are presented, of two-fermion events produced in e+e- collisions at centre-of-mass energies from 189 to 209 GeV at LEP, measured with the ALEPH detector. Results for e+e-, μ+μ-, τ+τ-, qq̄, bb̄ and cc̄ production are in agreement with the standard model predictions. Constraints are set on scenarios of new physics such as four-fermion contact interactions, leptoquarks, Z′ bosons, TeV-scale quantum gravity and R-parity violating squarks and sneutrinos.

Highlights

  • In the years 1995–2000, the LEP collider delivered e+e− collisions at centre-of-mass energies from 130 to 209 GeV

  • In order to reduce the uncertainties related to interferences between ISR and FSR, the exclusive cross sections and asymmetries are not extrapolated to the full acceptance

  • It is possible to reduce the dependence of this measurement on the b efficiency estimated from the simulation by replacing the product εbσb with Ndbata/L, where Ndbata is the number of b events in the data and L is the integrated luminosity

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Summary

Introduction

In the years 1995–2000, the LEP collider delivered e+e− collisions at centre-of-mass energies from 130 to 209 GeV. Measurements o√f the e+e− → f fprocess with the ALEPH detector up to s = 183 GeV have been published in [1]. The results obtained at seven additional energy values are presented in this paper with analyses largely unchanged with respect to [1]. The seven centre-of-mass energies are listed, together with the corresponding luminosities. In the year 2000 the luminosity was delivered in a range of energies. 3 presents the event generators used for the simulation of the signal and backgrounds, and Sect.

The ALEPH detector
Cross section definition
Hadronic final states
Heavy-flavour production
Measurement of Rb
Measurement of Rc
Measurements of AbFB and QFB
Interpretation in terms of new physics
Contact interactions
R-parity violating sneutrinos
Leptoquarks and R-parity violating squarks
Extra Z bosons
Limits on TeV-scale gravity
Findings
Conclusions
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